Modified melamine resins



PstentedMayZi, 1950 UNITED STATES PATENT OFFICE No Drawing. ApplicationDecanter a, ll, ScrislNo. 718.26!

I! cum. (cl. Ill-$7.)

This invention relates to new surface coating resins. More particularly,the invention relates to melamine resins modified with arylsulfonamides.

The reaction products of methylol meiamines with alcohols have becomeimportant in the synthetic coating field. particularly in combinationwith conventional surface coating resins. The modified methylolmelamines speed the curing of the conventional resins and improve theircolor retention, chemical resistance and abrasion resistance. However,the known alcohol-modified methylol melamines have limited compatibiliwwith other surface coating resins and when used in large enough quantityto effect maximum improvement of said resins, the gloss of the iinalcoating is seriously impaired. Furthermore, when used with acidic resinssuch as high acid number allwd resins, the varnish obtained is unstableand tends to set up in storage.

It is an object of this invention to provide new surface coating resins.

A further object is to provide resins which may be admixed with othersurface coating resins to improve the properties of the latter.

' These and other objects are attained by reacting an aryl sulfonamidewith melamine, formaldehyde and alcohols.

The following examples are given in illustration and are not intended aslimitations upon the scope of this invention. Where parts are mentioned,they are parts by weight.

Emmple I Parts 'Helamine 100 'Santiciser 9 43 Formalin (37%formaldehyde) 463 92% butanoi 505Santiciserilisatrsdenameforsmixiureofortho and para toluenesnlionamides.

The melamine, Santieizer 9 and Formalin were placed in a reaction vesseland the pH of the 833M910 II Example I was repeated except that theSanticiseril wosnotaddeduntilafterthe reaction between melamine andthel'm'maiintomake methylol melamine was completed. The resultant resinappeared to be slightly softer than that made by Example I. butotherwise was identical with it.

during the distillation, until the distillate con- II trample III partsof benzene sulfonamide were substituted for the Santiciner 9 shown inExample I. The reaction proceeded as described in Example I and a clear,colorless resin solution was obtained from which a clear. colorless illmwas cast to provide a hard, brittle film having a high gloss.

Emilie]? Parts Melamine- Para toluene sulfonamide 43 Formalin 463Methanol 505 The melamine. para toluene sulfonamide and Formalin wererefluxed at atmospheric pressure at a pH of approximately 8-9 obtainedwith 5% aqueous sodium hydroxide until the reaction medium been! to becloudy. At this point. the methanol was added and the solution was madeslightly acid by the addition of formic acid. The resultant mixture wasrefluxed at atmospheric pressure for about 2 hours and then water andmethanol were removed and separated by fractional distillation, the drymethanol being returned to the reaction vessel. In this example, it isnottoresortto aseotropic distillation. The product was a methanolsolution of methyioi melamine modified by para toluene sulfonamide andmethanol.

In contrast to many of the commercial methylol melamine-alcoholcondemation products, the products obtained in the examples werecompatibleinallwithalkydresinsin generaltoimprovetheirharmsurfaceglossamen 3 and resistance to weathering and cmmicals. The present productsalso showed an increased coinpatibility with other surface coatingmaterials such as cellulose derivatives, phenolic resins, etc.

The aryl sulfonamides shown in the examples may be replaced in whole orin part by other aryl sulionamides such as ring-substituted bennenesulionamides in which the substituent on the ring may be an alkyl group.The amount of aryl sulfonamide used may be varied over a wide range. Aslittle as of a moi per inol oi melamine may be used and the amount ofaryl sulfonamide may be increased to more than 1 mol per mol ofmelamine. A preferred range to obtain advantageous surface coatingresins is from about 0.2 to 0.4 mol of aryl sulfonamide per moi ofmelamine.

The amount of formaldehyde used may vary from 1 moi per moi of melamineto 6 or more mols per moi of melamine.

Butanol and methanol were disclosed in the examples as lcohols to bereacted with the methylol melamine. They may be substituted in whole orin part by other alcohols and substituted alcohols including aliphatic,cycloaliphatic, aromatic, nitro, and amino alcohols, such as ethanol,propanol, isopropanol, pentanols, octanols, lauryl alcohol, cetylalcohol, stearyl alcohol, cyclohexanol, benzyl alcohol, cinnamylalcohol, allyl alcohol, z-nitro-i-butanol, 2-nitro-2- methyl-l-propanol,2-nitro-2-methyl-l,3 propane diol, 2-nltro-2-ethyl-i,3-propane diol,tris (hydroxy methyl) nitro methane, z-amino-l-butanol,z-arnlno-2-methylei-propanol, 2-amino-2- methyl-1.3-propane diol,2-amino-2-ethyl-l,3-

propane diol, tris (hydroxy methyl) amino methane, etc. Mixtures of twoor more alcohols may be used if desired.

The pH of the reaction mixture should be kept on the alkaline side,about 8-9, until the reaction between melamine and formaldehyde to iormmethyiol melamines is substantially completed. At this point the pHshould be adjusted to the acid side. Various acids such as formic acid,acetic acid, hydrochloric acid, phosphoric acid, etc. may be used tocreate the acid pH. The reaction may also be carried out at temperatureslower than the reflux temperature, for example, to C. to obtainessentially monomeric low molecular weight resins, if desired.

The solutions produced by the process of this invention as illustratedin the examples may be diluted with other surface coating solvents orthinners such as dipentene, butyl cellosoive, phenyl cellosolve, dibutylphthalate, benzene, toluene, etc. 11' the presence oi butanol, methanol,or other low boiling solvent is objectionable, they may; be removedfromthe solutions by vacuum distillation and the resin thus obtained may bethen dissolved in higher boiling solvents and thinners.

The resins 0! this invention may be used as a surface coating resinalone or modified by conventional additives such as natural or syntheticresins or other materials, including copal, kauri, gum tragacanth,met-boxy cellulose, casein, etc., and dyes, pigments, lakes, fillers,etc.

The resins of this invention are especially advantageous for use inmodifying alkyd resins for surface coatings. They are compatible in allproportions with alkyd resins in general, including unsaturated alkydresins and improve the color, hardness, gloss, chemical resistance andabrasion resistance of 'the aliwd resins without impairing thelihy olpropertiesotthecoatingsderived therefrom. Buch compositions are morespecifically and claimed in application Serial No. 718,370 flied Dec.24, 1948, by myseli and Frank J. Hahn.

The aryl sulionainide modified melamine resins may be plasticized withlow molecular polymers or a-methyl styrene to produce molding compoundshaving exceptionally high resistance to alkali. Such compounds areparticularly useiul in making washing machine agitators and otherarticles which are frequently in contact with alkaline solutions.

As shown above, the solvents may be removed from the resins oi thepresent invention by vacuum distillation or other suitable means toproduce materials which are solid and friable at ordinary temperatures.In this respect, the present resins are vastly difierent from the usualalkylated melamine-formaldehyde products which cannot be dried down toform hard, solid, friable resins without loss of solubility. The resinsthus obtained may be mixed with various plasticizers, resins, drying andnon-drying oils, etc. The resins or mixtures may be used tor laminating,textile treating or the like. 1:! desired, they may be dissolved insuitable solvents prior to their use as laminating or textile treatingagents.

The new resins may also be used in combination with urea, urea-melamine,melamine, thiourea and phenolic resins and may be incorporated inprinting ink vehicles, oleoresino'us varnishes, oils and oil varnishes.etc.

It is obvious that many variations may be made in the processes andproducts of this invention without departing from the spirit and scopethereof as defined in the appended claims.

What is claimed is:

1. A surface coating resin comprising the heatreaction product of amethyiol melamine-alcohol condensation product with an aryl sulionamidetaken from the group consisting of benzene sulionamide andring-substituted benzene sulfonamides wherein the substituent is analkyl group. the ratio of said aryl sulfonamide to chemically combinedmelamine varying from 0.1 to 1 mol per mol of melamine.

2. A surface coating resin as in claim 1 wherein the aryl sulionamide isa mixture of orthoand para-toluene sulfonamides.

3. A surface coating resin as in claim 1 wherein the aryl suiionamide isbenzene sulionamide.

4. A surface coating resin as in claim 1 wherein the aryl sulionamlde ispara-toluene sulfonamide.

5. A surface coating resin as in claim 1 wherein the ratio of arylsulfonamide to chemically combined melamine varies from 0.2 to 0.4 molper moi of melamine.

6. A process for producing a surface coating resin which comprisesreacting together under alkaline conditions melamine, formaldehyde andan aryl sulfonamide taken from the group consisting of benzenesulionamide and ring-substituted benzene sulfonamides in which thesubstituent is an alkyl group, the molar ratio of melamine to arylsuifonamide varying from 1:0.1 to 1:1 and then reacting the product withan alcohol under acid conditions.

7. A process as in claim 6 wherein the sulfonamide is benzenesulfoamide.

8. A process as in claim 6 wherein the aryl sulioanmide is para-toluenesulionamide.

9. A process as in claim 6 wherein the aryl sulfonamide is a mixture oforthoand paratoluene aulfonamidsc.

aryl

10. A-proceaaasinclaimfiwii'ereinthemolar ratio of melamine to arylsulionamide varies i'rom 1:02 to 1:0.4.

11. A coating composition comprising the heat reaction product of a.methylol-melamine-alcohol condensation product with an aryl sulionamidetaken from the group consisting of benzene suli'onamide andring-substituted benzene sul- Ionamides in which the substituent is analkyl group, the ratio 01' combined melamine to aryl suli'onamide being1 moi of melamine to 0.1 to 1 mol of aryl suli'onamide, said resin beingdissolved in an organic solvent.

MILTON J SCOTT.

6 REFERENCES crrEn The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 2,197,357 Widmer Apr. 16, 19402,320,817 D'Alelio June 1, 1943 2,326,725 Jayne Aug. 10. 1943 2,327,772DAlelio Aug. 24, 1943 2,331,376 D'Alelio Oct. 12. 1943 2,368,451D'Alelio Jan. 30, 1945 FOREIGN PATENTS Number Country Date 104,882Australia July 'I, 1938

1. A SURFACE COATING RESIN COMPRISING THE HEATREACTION PRODUCT OF AMETHYLOL MELAMINE-ALCOHOL CONDENSATION PRODUCT WITH AN ARYL SULFONAMIDETAKEN FROM THE GROUP CONSISTING OF BENZENE SULFONAMIDE ANDRING-SUBSTITUTED BENZENE SULFONAMIDES WHEREIN THE SUBSTITUENT IS ANALKYL GROUP, THE RATIO OF SAID ARYL SULFONAMIDE TO CHEMICALLY COMBINEDMELAMINE VARYING FROM 0.1 TO 1 MOL PER MOL OF MELAMINE.